This invention relates to a safety needle. More particularly, this invention relates to a safety needle employing a blunt cannula to protect a sharp edged needle.
As is known, one major problem with hypodermic needles as well as other needles is the threat of cutting oneself or another thereby exposing a blood vessel to the environment. This has become especially important in a hospital atmosphere where AIDS patients or AIDS members of a staff can infect others by having their blood interact, for example, by touching another person.
Various techniques have been proposed to overcome this problem. For example, in some cases, use has been made of a shield or cap which is placed over a needle after use. Generally, this is intended to only allow a one-time use of the needle with an automatic covering system which prevents further use. However, during actual use of such a needle the needle does not remain totally protected. Further, if the needle is re-used, there is no provision to sheath the needle.
U.S. Pat. No. 4,629,453 describes a protection device for a hypodermic needle which uses a protective cap which can be fitted over a needle when the needle is not in use.
U.S. Pat. No. 4,735,618 describes a protective enclosure for hypodermic needles which employs a cap-like needle guard which is positioned about a free end of a needle while being connected via collapsible arms to a tubular sleeve mounted about a needle housing. When in use, the cap is pressed against a patient under a sufficient force to cause collapsing of the collapsible arms so that the cap slides back over the needle. However, when not intended for use, any accidental pushing in on the cap can cause an inadvertent needle stick.
U.S. Pat. No. 3,134,380 describes a shielded hypodermic needle wherein a needle is sheathed within a collapsible tube so that upon collapsing of the tube, the needle is exposed. In addition, a spring is provided within the tube so as to return the collapsed tube to an extended state.
U.S. Pat. No. 4,725,267 describes the use of a resilient collapsible sheath which can be mounted over a needle to contain the needle when not in use.
U.S. Pat. No. 4,695,274 describes a removable needle attachment consisting of a needle-holding member and a safety jacket. As described, the jacket is provided with a slot which receives a guide tab of the needle-holding member so as to prevent sliding of the safety jacket back and forth on the needle holding member in order to prevent piercing of the needle through a wall of the safety jacket. However, in such a construction, as in other similar constructions, a risk of inadvertent needle sticking occurs should the guide tab be disposed in an unlocking condition within the slot.
U.S. Pat. No. 5,472,430 describes the use of a spring loaded blunt cannula which is carried within the lumen of the needle. When the spring is actuated, the blunt cannula extends beyond the needle thereby preventing it from cutting. However, in such a design there is required a twisting of the blunted cannula to achieve movement. In turn, this creates an unnatural required motion of the user to achieve movement and locking of the blunt cannula in place.
U.S. Pat. No. 5,472,430 describes a stationary needle through which a blunt needle is telescopically moved to extend beyond the sharpened edge of a sharpened needle. In this manner, the sharpened edge is protected or sheathed to prevent accidental cutting. To achieve this condition only the blunt needle may move relative to the fixed sharpened needle. When moved, the blunt needle is rotated to achieve a lock generally in the safety position. Limitations of this design include: the blunt needle must be rotated to obtain a lock and the attachable portion (normally a luer hub) is separated from the housing which performs the operation of moving the blunt needle and therefore presents a generally unmanageable obstruction to the user when manipulating the blunt needle. It has been found that the user has difficulty in placing the sharpened needle in a safety position by rotating the detent to activate the spring or arming the sharpened needle again by a rotation of the detent prior to movement of the blunt needle. Should the moveable member be the sharpened needle, then there is the danger that rotating the sharpened needle will result in damage if the sharpened needle is within the body or to the user if a part of the user""s body comes in contact with the needle edge.
Accordingly, it is an object of the invention to provide a needle assembly with a protective interior blunt needle.
It is another object of the invention to prevent inadvertent passage of a needle from a protective state outside of a blunt needle to an armed state capable of cutting.
It is another object of the invention to provide for movement of a sharpened needle without rotation to achieve a lock.
It is another object of this invention to provide a natural means for a user to move a needle from an armed state to an unarmed state.
Briefly, the invention provides a safety needle that is comprised of a housing, a blunt cannula mounted in and extending from the housing, a slider movably mounted in the housing and on the blunt cannula for movement between a locked position and an unlocked position and a needle mounted in and extending from the slider in concentric relation to the blunt cannula. The needle has a sharpened end projecting beyond the blunt cannula in the locked position of the slider and is retracted over the blunt cannula in the unlocked position of the slider.
In accordance with the invention, the safety needle has a spring in the housing for biasing the slider from the locked position towards the unlocked position. The invention also provides a manually operated actuator that is movable between a first position blocking movement of the slider from the locked position to the unlocked position and a second position allowing movement of the slider from the locked position to the unlocked position under a biasing force of the spring.
In one embodiment, the housing has an elongated slot while the actuator is mounted on the slider to move transversely within the slot of the housing between the first and second positions thereof. In particular, the slot has an enlarged aperture disposed in a location corresponding to the locked position of the slider, while the actuator has a stem that slides within the slot, as well as an enlarged boss for seating in the enlarged aperture in the first position of the actuator. Thus, when the boss is seated in the enlarged aperture, the slider is restrained against movement under the biasing force of the spring. However, when the boss is moved out of the enlarged aperture, the stem is free to slide within the slot in the housing under the biasing force of the spring. This, in turn, allows the slider to move within the housing.
In this embodiment, the actuator is integral with the slider. To this end, the actuator has an arm that receives the stem at one end and that extends from the slider at the opposite end in cantilever relation. In addition, the actuator includes a button on the stem for manual pushing of the stem into the housing in order to move the boss out of the enlarged aperture.
In operation, when the safety needle is used in making a venipuncture in a patient, the needle is in an extended position relative to the blunt cannula so as to project beyond the cannula. Upon depressing the button of the actuator, the slider moves under the bias of the spring to retract the needle over the cannula so that the cannula protects against an inadvertent xe2x80x9cstickxe2x80x9d.
In another embodiment, the actuator is slidably mounted transversely within the housing to move between a position in which the slider is locked and a position in which the slider is unlocked. In this embodiment, the slider has a groove while the actuator has a stem selectively positioned in the groove in the first position of the actuator and positioned outside the groove in the second position of the actuator.
For example, in this embodiment, the groove in the slider is an annular groove and the stem has an aperture for passage of the slider therethrough. Thus, when the actuator is in a raised first position, the stem fits into the groove of the slider to prevent the slider from moving under the bias of the spring. When the actuator is depressed, the stem moves out of the groove of the slider to permit the slider to pass through the aperture in the stem under the biasing force of the spring.
In this embodiment, a guard is slidably mounted on the housing for movement between a blocking position to block movement of the actuator and a release position to allow movement of the actuator. This reduces the risk that the actuator may be inadvertently actuated.
In order to have the actuator cooperate with the guard, the stem has a reduced recess communicating with the aperture through which the slider passes. In addition, the guard has a body extending into the aperture in the blocking position to block movement of the actuator and a reduced section extending into the recess of the actuator when in the released position to unlock the actuator.
Thus, when the guard is in the blocking position, the body on the guard is disposed when the aperture in the stem of the actuator to prevent the actuator from being depressed into the housing. When the guard is moved into the unblocking position, the reduced section of the guard is aligned with the reduced recess in the actuator stem, the actuator is then free to be pushed into the housing so that the reduced section of the guard is accommodated within the reduced recess while the stem of the actuator moves into a position to allow the slider to move through the aperture in the actuator stem under the biasing force of the spring.
In this embodiment, the actuator includes a button on the stem for manual pushing of the stem into the housing. In addition, the guard is provided with an indicator which is positioned outside the button when the guard is in the blocking position and is positioned under the button when the guard is in the release position.
In still another embodiment, wherein the actuator is separate from the slider, an actuator depressor is slidably mounted on the housing for moving the actuator into the housing. In this embodiment, the actuator depressor includes a recess receiving the actuator and a sloped wall in the recess abutting the actuator whereby, upon movement of the depressor along the housing, the sloped wall moves the actuator into the housing and into the second position thereof.
In this latter embodiment, the actuator depressor serves to prevent inadvertent depressing of the actuator into the housing by bridging over the actuator. Also, the actuator depressor provides a surface which may be manually actuated to slide along the housing in order to move the actuator into the housing to release the spring biased slider.
A sheath may be slidably mounted on and over the needle outside the housing. Typically, the safety needle would be withdrawn from the sheath to leave the sheath in place. In order to provide for an automatic actuation of a spring-biased slider, a gripper arm extends from the actuator depressor to selectively engage the sheath. Thus, as the housing is pulled away from the sheath, the gripper arm is initially in engagement with the sheath so that the actuator depressor is pulled along the housing, thereby depressing the actuator into the housing to unlock the spring-biased slider. Thus, once the housing has been separated from the sheath, the needle is automatically retracted over the blunt cannula into the protected position.
In order to facilitate disengagement of the gripper arm on the actuator depressor from the sheath, the gripper arm may be spring-mounted on the actuator depressor to be biased away from the sheath in a predetermined location of the actuator depressor on the housing.